The treatment of waste water has a number of problems associated therewith. In particular, noxious odors in sewage treatment facilities result partially from ammonia gas and the partial anaerobic digestion of proteinaceous wastes. Concomitant with the formation of ammonia is an increase in the pH of the system. Accordingly, organisms sensitive to high pH and/or to ammonia are killed. In addition, after the depletion of oxygen due to the oxidation of ammonia, those organisms capable of producing sulfides grow to a large extent, which in turn causes significant odor problems.
In order to overcome this problem, methods for retrading and when possible for preventing the formation of free ammonia have been suggested. In particular, the bacteria known as Nitrosomonas and Nitrobacter cooperate to convert ammonia to nitrate. However, the presence of nitrate tends to limit the production of additional amounts of nitrate. Moreover, acid is formed during oxidation of the ammonia. In many systems, denitrifying bacteria are also required to convert the nitrate to nitrogen gas (since there are health limits for nitrate levels in water).
Therefore, an object of the present invention is to provide microorganisms, which convert ammonia to nitrogenous gases, without the production of significant amounts of nitrate. This could eliminate the necessity for additional bacteria to effect denitrification.
It is further recognized that many of the bacteria employed in wastewater treatment die quickly when left dormant in dilute suspension or form spores that require time to germanate before becoming metabolically functional. Therefore, a further object of the present invention is to provide a microorganism which can be stored over relatively long periods of time (several months) without significantly losing its deammonifying capabilities.
Moreover, various bacteria capable of metabolizing ammonia are not effective in the presence of carbonaceous substrates. In such case, two separate chambers are required for treatment; the first of which is to treat the carbonaceous substrates, followed by oxidizing the ammonia. The microorganisms of the present invention can act in the presence of carbonaceous substrates. Accordingly, a waste treatment system employing the microorganisms of this invention makes it possible to employ only one instead of multiple chambers in a waste-treatment system.
The process of preparing the microorganisms utilizes a solid medium which provides for a number of desirable advantages including easy storage, transportation and utilization to full advantage. Also, since the microorganisms are present on a solid medium, seeding of the waste-systems is convenient, which, in turn, reduces the time between start-up and steady state. Moreover, the culture can be readily added in a continuous manner.